Iron is essential to most life forms and to normal human physiology. Iron is an integral part of many proteins and enzymes that maintain good health. In humans, iron is an essential component of proteins involved in oxygen transport, Dallman, P. R., “Biochemical Basis for the Manifestations of Iron Deficiency,” Ann. Rev. Nut., 6, p. 13-40 (1986). Iron is also essential for the regulation of cell growth and differentiation, Andrews, N. C., “Disorders of Iron Metabolism,” N. Eng. J. Med., 341, p. 1986-95 (1999). A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity, Haas, J. D., Brownlie, T., “Iron Deficiency and Reduced Work Capacity: a Critical Review of the Research to Determine a Causal Relationship,” J. Nut., 131, p. 691S-6S (2001); Bhaskaram, P., “Immunobiology of Mild Micronutrient Deficiencies,” Br. J. Nut., 85, p. S75-80 (2001).
Several oral compositions are known for the use as nutritional or dietary supplement containing iron. Known compositions include multivitamins and mineral supplements in various oral dosage forms that contain iron to alleviate the symptoms of iron deficiency. One drawback of most such oral supplements is that iron can give an oral dosage form a bad metallic taste. Accordingly, most such oral supplements limit the amount of iron in the formulation or use taste masking technology such as coating of iron containing granules or tablets, admixing taste masking flavors or using gelatin coated delivery systems, such as capsules or gelcaps. These approaches increase the complexity of manufacturing operation, increase the cost of the supplement, and can affect the effectiveness of the supplement, especially for persons who have difficulty swallowing tablets, capsules or gelcaps.
Other metals included in many nutritional supplements, like copper, can also impart an unpleasant metallic taste to oral supplements. Oral supplements containing copper suffer from the same drawbacks as oral supplements containing iron.